Oscillating middle axle for a utility vehicle

ABSTRACT

A utility vehicle is provided with a middle axle that is mounted at the end of a bogey beam for both flotational and oscillatory movement relative to the frame of the vehicle. The middle axle is restrained longitudinally by support links that are pivotally connected to the frame at a location that is forward of the rear drive axle. The middle axle is formed by a pair of stub axles interconnected by a support beam that is pivotally connected to the rearward end of the bogey beam. Vertical movement of the middle axle support wheels results in a corresponding vertical movement of the rearward end of the bogey beam and a rotation of the support beam about its pivotal connection on the bogey beam. The oscillatory movement is accomplished by a pivotal connection via a ball joint between a central support bracket mounting the transverse support beam to the longitudinally extending bogey beam.

FIELD OF THE INVENTION

The present invention relates generally to off-road motor vehicles, suchas utility or recreational vehicles, and more particularly, to a middleaxle apparatus for a utility vehicle to provide oscillatory movement forthe middle axle.

BACKGROUND OF THE INVENTION

Small off-road vehicles such as utility or recreational vehicles arebecoming popular for recreational and other general purpose off-roadusage. Such utility vehicles can be found in U.S. Pat. No. 4,706,770.These utility vehicles have found usage on golf courses and at sportingevents, and are particularly adaptable for utilization on a farm. Thistype of flexibility in the wide variety of uses necessitates a vehiclethat is highly flexible, highly maneuverable and the like. This demandsa vehicle that will afford a high degree of maneuverability and ease ofsteering.

Steering characteristics of known utility vehicles provide poor turningperformance. Known utility vehicles have turning clearance circleshaving a diameter greater than twenty-one feet. The use of independentfront wheel suspension mechanisms on known utility vehicles, coupledwith the mounting of the rack and pinion systems on the frame of thevehicle, introduces minor king pin rotations as the steering tires rideover ground undulations. Such construction reduces steering precisionand can accelerate the wear of the tires on the steering axle.

Placing a load on the utility vehicle typically results in a variationin the steering performance of known utility vehicles. For example, oneknown embodiment having a front steering axle, a rear drive axle, and amiddle drive axle carries the load placed on the vehicle on the middleand rear axles, resulting in proportionately less weight on the steeringaxle and a reduction in maneuverability. Accordingly, known utilityvehicle construction results in a significant influence on the steeringperformance by the load carried on the vehicle. Preferably, loads shouldnot change the steering characteristics for any vehicle.

Furthermore, conventional utility vehicle construction mounts the middleaxle directly to the frame of the vehicle, resulting in a harsh ridecharacteristic and direct application of any load placed into the loadbed onto the middle axle as well as the rear drive axle. Furthermore,the middle axle, in being fixed to the frame, is incapable ofoscillatory movement, i.e. movement from side-to-side about alongitudinally extending pivot axis, which would further enhance theride characteristics of the utility vehicle. It would, therefore, bedesirable to enhance the ride characteristics, as well as the steeringperformance of utility vehicles by distributing the weight of the loadsbeing carried in a different manner and by providing a mechanismpermitting the middle axle to oscillate to better follow groundundulations.

It is therefor desirable to provide a utility and recreational vehiclethat overcomes the disadvantages of the known prior art utilityvehicles.

SUMMARY OF THE INVENTION

Accordingly, an important object of the present invention is to providea middle axle support apparatus for a utility vehicle that is notdirectly mounted to the frame of the vehicle.

It is another object of this invention to provide a support mechanismfor the middle axle on a utility vehicle to provide flotational andoscillatory movement of the middle axle relative to the frame.

It is a further object of this invention to provide support for themiddle axle of a utility vehicle in such a manner as to prevent the loadplaced thereon from overcoming the steering operation of the front axle.

It is a feature of this invention to add a bogey beam extendinglongitudinally at the center line of the utility vehicle to interconnectthe front and middle axles.

It is another feature of this invention that a portion of the loadplaced into the load bed of the utility vehicle will be distributed tothe bogey beam to be re-distributed to the front and middle axles in apredetermined proportion.

It is an advantage of this invention that maneuverability of the utilityvehicle is greatly increased during load bearing operations.

It is a another advantage of this invention that the middle axleprovides the ability to oscillate and float relative to the frame of theutility vehicle.

It is still another advantage of this invention that the ridecharacteristics of a utility vehicle are improved, particularly underload bearing conditions.

It is still another feature of this invention that the loads placed onthe load bed of the utility vehicle are proportionally distributedbetween the front steering axle and the middle drive axle of the utilityvehicle.

It is a yet another advantage of this invention that the flotationalmovement of the middle axle provides sufficient slack in the drivemechanism to permit the chain drive to twist slightly in response to theoscillation of the middle axle.

It is yet another feature of this invention that a central supportbracket pivotally connecting a support beam for the middle axle to thebogey beam allows a Rotational movement of the middle axle with thebogey beam and with longitudinally stabilizing support links.

It is a further object of this invention to provide a middle axlesupport mechanism for an off-road vehicle that is durable inconstruction, inexpensive to manufacture, carefree in maintenance, easyto assemble, and simple and effective in use.

These and other objects, features, and advantages are accomplishedaccording to the present invention by providing a utility vehicle havinga middle axle that is mounted at the end of a bogey beam for bothflotational and oscillatory movement relative to the frame of thevehicle. The middle axle is restrained longitudinally by support linksthat are pivotally connected to the frame at a location that is forwardof the rear drive axle. The middle axle is formed by a pair of stubaxles interconnected by a support beam that is pivotally connected tothe rearward end of the bogey beam. Vertical movement of the middle axlesupport wheels results in a corresponding vertical movement of therearward end of the bogey beam and a rotation of the support beam aboutits pivotal connection on the bogey beam. The oscillatory movement isaccomplished by a pivotal connection via a ball joint between a centralsupport bracket mounting the transverse support beam to thelongitudinally extending bogey beam.

The foregoing and other objects, features, and advantages of theinvention will appear more fully hereinafter from a consideration of thedetailed description that follows, in conjunction with the accompanyingsheets of drawings. It is to be expressly understood, however, that thedrawings are for illustrative purposes and are not to be construed asdefining the limits of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The advantages of this invention will be apparent upon consideration ofthe following detailed disclosure of the invention, especially whentaken in conjunction with the accompanying drawings wherein:

FIG. 1 is side perspective view of a utility vehicle incorporating theprinciples of the present invention;

FIG. 2 is a top plan view of the utility vehicle of FIG. 1, the seatsand control apparatus being shown in dashed lines, the frame and axlesbeing shown in phantom;

FIG. 3 is a top plan view of the frame and drive mechanism with thechassis removed for purposes of clarity;

FIG. 4 is an enlarged cross-sectional view of the utility vehicle takenalong lines 4—4 of FIG. 3 to show the drive mechanism and theorientation of the bogey beam supporting the front steering axle and themiddle drive axle;

FIG. 5 is an enlarged cross-sectional view of the utility vehicle takenalong lines 5—5 of FIG. 3 to show an elevational view of the middledrive axle;

FIG. 6 is an enlarged cross-sectional view similar to that of FIG. 4 butshowing flotational movement of the middle axle, the normal position ofthe middle axle being shown in phantom; and

FIG. 7 is a top plan view of the frame and drive mechanism of analternative embodiment of the utility vehicle in which the engine andtransmission are mounted on a module that is partially supporteddirectly by the middle axle.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIGS. 1-3, a utility vehicle incorporating the principlesof the present invention can best be seen. Any left and right referencesare used as a matter of convenience and are determined by standing atthe rear of the vehicle and facing forwardly into the direction oftravel.

The utility vehicle 10 includes a frame 12 supported above the ground Gby a pair of steered wheels 22, 23 mounted on a front steering axle 20and by a pair of driven wheels 25 mounted on a rear drive axle 24. Inthe preferred embodiment depicted in FIGS. 1-3, a middle drive axle 27is also provided with a pair of opposing support wheels 28. The frame 12supports an operator compartment 13 including seats 14 for the comfortof the operator and control apparatus, such as a conventional steeringwheel 15 and a gear shift lever 16. A throttle control 17 and a brakecontrol 18, along with other conventional control devices, are alsoincluded within the operator compartment 13 for the control of thevehicle 10. The frame 12 also supports a load bed 19 rearwardly of theoperator compartment 13 over the middle and rear drive axles 27, 24respectively, to carry cargo over the surface of the ground G.

Referring now to FIG. 3, the frame 12 with the axles 20, 24, 27 mountedthereon can best be seen. The rear drive axle 24 is rotatably supportedon the frame 12 and is powered by a drive mechanism 26 powered by anengine 11 supported by the frame 12. The middle axle 27 is pivotallysupported from the frame 12 by a pair of support links 29 and isconnected to the rearward end of a bogey beam 30, which will bedescribed in greater detail below. The middle axle 27 is preferablyformed as a pair of stub shafts 27 a, 27 b connected to said respectivesupport links 29. A support beam 32 is pivotally mounted on a rearwardend of the bogey beam 30 for oscillatory movement about a longitudinallyextending pivot axis 33. The support wheels 28 on the middle axle 27 aredriven by respective chain drives 26 a to provide a four wheel drivecapability for the vehicle 10.

Front axle 20 and the mounting member 35 are attached to the forward endof the bogey beam 30, and, therefore, also pivot about axis 33 a. Thebogey beam 30 is pivotally connected to the frame 12 by a pivot assembly37 positioned beneath the operator compartment 13 to provide anoscillation of the bogey beam 30 about the transverse pivot axis 38.Accordingly, the front steering axle 20 and the middle axle 27 generallyoscillate in opposing vertical directions on opposite ends of the bogeybeam 30 due to the pivotal mounting thereof by the pivot assembly 37.

The pivot assembly 37 can be formed as a simple pin assembly connectingthe bogey beam 30 to the frame 12 of the vehicle 10 to define thetransverse pivot axis 38, as is shown in the drawings. The pivotassembly 37 can also suspend the bogey beam 30 from the frame 12 byproviding a link (not shown) that pivotally connects at one end to thebogey beam 30 and is centrally connected to the frame 12 with theopposing end of the link being connected to a spring mechanism (notshown) that provides some resiliency between the bogey beam 30 and theframe 12. Under such a suspended bogey beam arrangement, the transversepivot axis 38 would be located at the pivotal connection between thelink (not shown) and the bogey beam 30, but would be vertically movablerelative to the frame 12 about the pivotal connection between the link(not shown) and the frame 12, the spring mechanism (not shown)interconnecting the frame 12 and the link (not shown) to offset forcesencountered by the bogey beam 30. The location of the central pivot onthe link (not shown), pivotally connecting the link to the frame 12,being positioned between the opposing ends of the link to provide thedesired resiliency for the selected size of the spring mechanism.

Any load placed in the load bed 19 will be transferred to the rear axle24 through the mounting thereof with the frame 12 and to the bogey beam30 via the pivot assembly 37. The weight carried by the bogey beam 30will be shared in a proportionate manner between the front steering axle20 and the middle axle 27. The respective proportions will be determinedby the location of the pivot assembly 37 along a length of the bogeybeam 30. Accordingly, any load transferred to the bogey beam 30 willalways be proportionately divided between the front steering axle 20 andthe middle axle 27. As a result, the steering characteristics will notbe impacted by any load placed into the load bed 19, as the middle axle27 cannot overpower the front steering axle 20.

The front steering axle 20 is operatively associated with a steeringmechanism 40 to effect turning movement of the steered wheels 22, 23.The steering mechanism 40 is actuated through manipulation of thesteering wheel 15 by the operator through the universal connectinglinkage 42. The steering mechanism 40 includes a rack and pinionassembly 45 which includes a conventional pinion (not shown) rotatablyassociated with the steering wheel 15 and a conventional rack 47 that islinearly movable in conjunction with the rotation of the pinion 46 in aknown manner.

The rack 47 is pivotally connected to a first bell crank 50 at a firstconnection point 48. The first bell crank 50 is pivotally mounted on themounting member 35 for movement about a pivot 51. The connection point48 is positioned forwardly of the pivot 51 to effect pivotal movement ofthe first bell crank. The right steered wheel 22 includes a spuckle 52having a steering arm 53 extending rearwardly therefrom. The first bellcrank 50 is connected to the right steering arm 53 by a steering link 54that extends laterally and rearwardly from the first bell crank 50 tothe rearward end of the steering arm 53.

The steering mechanism 40 also includes a second bell crank 55 pivotallymounted on the mounting member 35 for movement about a pivot 56. Thesecond bell crank 55 is connected to the first bell crank 50 by a tierod 60 for coordinated movement therebetween. Accordingly, pivotalmovement of the first bell crank 50 is transferred to the second bellcrank 55 through connection with the tie rod 60. The left steered wheel23 includes a spuckle 57 having a steering arm 58 extending rearwardlytherefrom. The second bell crank 55 is connected to the left steeringarm 58 by a steering link 59 that extends laterally and rearwardly fromthe second bell crank 55 to the rearward end of the steering arm 58.Accordingly, the left and right steered wheels 22, 23 are steered inconcert with one another in response to a manipulation of the steeringwheel 15 by the operator.

Referring now to FIGS. 3-5, the details of the bogey beam constructionand the support of the middle drive axle 27 can best be seen. Thesupport beam 32 at the rear end of the bogey beam 30 has the stub axles27 a, 27 b mounted directly to the laterally opposing ends of thesupport beam 32. The support beam 32 further has a pair of mountingbrackets 34 projecting rearwardly therefrom interiorly of the stubshafts 27 a, 27 b to pivotally connect with the support links 29. Thesupport links 29 pivotally interconnect the frame 12 just forwardly ofthe rear drive axle 24 and the mounting brackets 34 on the support beam32. While the drawings depict the support links 29 connected to theframe 12 and the rear drive axle 24 fixed to the frame 12, analternative configuration can suspend the rear drive axle 24 from theframe 12 such that the rear drive axle 24 is vertically movable relativeto the frame 12. In such a configuration, the support links 29 wouldpreferably be mounted to the rear drive axle 24 to be vertically movabletherewith, but pivotable about an axis that is not coincidental with theaxis of the rear drive axle 24. Furthermore, the pivotal connectionbetween the support links 29 and either the frame 12 or the rear driveaxle 24 will be positionally adjustable in a for-and-aft direction toprovide for adjustment of the tension in the chain drive mechanism 26 a,as will be described in greater detail below.

The support beam 32 is also connected to a central support bracket 31which, in turn, is connected to the rearward end of the bogey beam 30 bya ball joint 33 a defining the oscillation axis 33 which permits themiddle axle 27 to oscillate about a longitudinally extending axis 33 topermit the middle axle 27 to follow ground undulations. The centralsupport bracket 31 also defines a pivotal connection between the bogeybeam 30 and the support beam 32 such that the support beam 32 which isfixed to the central support bracket 31 is free to pivot about a boltdefining a transversely extending pivot axis 31 a that is eccentric withrespect to the transverse axis of the middle axle 27. Accordingly, themiddle axle 27 is capable of simultaneous pivotal movement about thetransverse axis 31 a and the pivotal connections between the supportlinks 29 and the mounting brackets 34. Preferably, the pivotalconnection between the support links 29 and the mounting brackets 34 arein alignment with the stub shafts 27 a, 27 b defining the middle axle27. The transverse pivot axis 31 a is located below the line of themiddle axle 27.

The pivotal connection of the support links 29 to the frame 12 (oralternatively to the rear drive axle 24) is preferably formed as anassembly that is longitudinally movable to control the tension in thechain drive mechanism 26 a. With specific reference to FIG. 4, theposition of the support beam 32 on top of the bogey beam depicts theforwardmost adjustable movement of the support links 29. One skilled inthe art will readily recognize that a fore-and-aft movement of thesupport link 29 will cause pivotal movement of the support beam 32 aboutthe transverse pivot axis 31 a carried by the rearward end of the bogeybeam 30. Accordingly, the normal operative position of the support beam32 will be at an orientation above the bogey beam 30 to allow for wearadjustment of the chain mechanism 26 a, similar to the solid linedepiction in FIG. 6.

In operation, as best seen in FIGS. 4-6, the middle axle 27 is free tofloat or to oscillate with respect to frame 12 of the utility vehicle10. The vertical movement of the middle axle 27 during flotationalmovement, or of even just one support wheel 28 during an oscillationmovement, is accommodated by the pivotal connections of the supportlinks 29, the bogey beam 30 and the support beam 32. The support links29 impose a controlled positional relationship with respect to themovements of the middle axle 27 relative to the rear drive axle 24, thuskeeping the chain drive mechanism 26 a in a proper drive transferringcondition. The support links 29 do not pivot on a center coincident withthe rear drive axle 24, but are pivoted at a point forwardly of the reardrive axle 24. Accordingly, the pivotal movement of the middle axle 27,as represented by the arc 29 a, will slightly shorten the distancebetween the middle axle 27 and the rear drive axle 24, thus allowing alittle slack in the chain drive mechanism 26 a to accommodate a slighttwisting of the chain drive mechanism 26 a when the middle axleoscillates about the ball joint 33 a. The floating movement of themiddle axle 27 about the rearward end of the support links 29, whosepivot axis is forward of the rear drive axle 24, will maintainacceptable tension in the chain drive mechanism 26 a for proper drivetransmission to the middle axle 27.

Furthermore, the middle axle 27 is mounted on the rearward end of thebogey beam 30 and any vertical floating movement of the middle axle 27must also move in conjunction with the limits imposed by the bogey beamstructure 30, as represented by the arc 30 a. Since the support beam 32is pivotally connected to the rear end of the bogey beam 30 by thecentral support bracket 31, the support beam 32 is capable of pivotingrearwardly about the pivot axis 31 a, as represented by the arc 32 a.Accordingly, the middle axle 27 vertically floats through pivot arcs 29a, 30 a, and 32 a that coordinate to provide substantially verticalmovement for the middle axle 27.

The vertical floating movement of the middle axle 27 is best shown inFIG. 6. The normal position of the middle axle 27 is shown in phantomlines, while the raised position of the middle axle 27 to accommodate aground undulation is shown in solid lines. The vertical movement of themiddle axle 27 raises the rearward end of the bogey beam 30, pivotingthe bogey beam 30 about the front axle 20, and slightly raises theoperator compartment 13 as represented by the vertical movement of thetransverse pivot 38. The pivotal movement of the middle axle 27 withrespect to the support links 29 results in a corresponding pivotalmovement of the central support bracket 31 about pivot axis 31 a,causing the support beam 32 to raise above the bogey beam 30. Thisflotational capability of the middle axle 27 results in a smoother ridefor the operator than is known in the prior art construction with themiddle axle 27 fixed to the frame 12.

The downward vertical movement of the middle axle 27 results in asimilar operation of the pivot arcs 29 a, 30 a, and 32 a. The downwarddisplacement of the middle axle 27 moves the rearward end of the bogeybeam 30 downwardly along the arc 30 a. The fixed length of the supportlinks 29 results in a pivotal movement of the support beam 32 about thetransverse pivot axis 31 a, raising the support beam 32 relative to thebogey beam 30.

Referring now to FIG. 7, an alternative configuration of the utilityvehicle can best be seen. The rear drive axle 24 carries a substantiallylarge portion of the weight of the vehicle 10 because of the directmounting of the rear drive axle 24 to the frame 12. The middle axle 27,being supported from the rearward end of the bogey beam 30, as isdescribed in greater detail above, carries a significantly smallerpercentage of the vehicle load as compared to the rear axle 24. Somere-distribution of the vehicle weight can be accomplished according tothe alternative embodiment shown in FIG. 7. Placement of the drive traincomponents, such as the engine 11 and the transmission 11 a, on asupport module 65 that is at least partially carried by the middle axle27 would relieve the rear axle 24 of a significant portion of thevehicle load. Furthermore, this support module 65 would provide aconstant load on the middle axle 27 and would be accommodated by thebogey beam 30 to provide consistent ride and steering characteristics.

The support module 65 on which the engine 11 and transmission 11 a aremounted is carried at the rearward portion thereof by a transversesupport link 69 connected to the opposing lateral sides of the frame 12.The connection between the support module 65 and the transverse supportlink 69 defines a transverse pivot axis to permit a relative pivotalmovement of the rearward end of the support module 65. The forward endof the support module 65 is carried directly by the middle axle 27, orby the support beam 32, so as to be weight bearing directly on themiddle axle 27. The support module 65 is preferably connected to thesupport beam 32 so as to be weight bearing on the middle axle 27. Theoperation of the support link 69 and the support module 65 forms asubstitute for the support links 29 described above with respect to theembodiment of FIGS. 1-6. Accordingly, the support module 65 is movablewith the middle axle 27 through both flotational and oscillatorymovements.

Preferably, in this alternative embodiment, the transmission 11 a ismounted on the support module 65 for direct driving connection with themiddle axle 27 so as to drive the support wheels 28 directly from thetransmission 11 a. Drive to the opposing rear wheels 25 is transmittedvia a pair of laterally opposed chain drives 26 a. Since the rear axle24 does not carry the weight of the engine 11 and transmission 11 a, therear axle 24 can be constructed as a pair of opposing stub shafts 24 a,24 b that are directly mounted to the opposing sides of the frame 12.Preferably, the configuration of the support beam 32 with the pivotedcentral support bracket 31, as described in detail above, will beutilized to provide both Rotational and oscillatory movements of themiddle axle 27 relative to the frame 12.

The invention of this application has been described above bothgenerically and with regard to specific embodiments. Although theinvention has been set forth in what is believed to be the preferredembodiments, a wide variety of alternatives known to those of skill inthe art can be selected within the generic disclosure. The invention isnot otherwise limited, except for the recitation of the claims set forthbelow.

Having thus described the invention, what is claimed is:
 1. A utilityvehicle comprising: a frame; a plurality of rear drive axles mounted tothe frame and having drive wheels rotatably supported thereon; a frontsteering axle having a pair of steered wheels pivotally mounted thereon;a middle axle having a pair of support wheels mounted at opposing endsthereof; and a longitudinally extending bogey beam pivotally connectedto the frame and having a forward end and a rearward end, said steeringaxle being connected to said forward end of said bogey beam and saidmiddle axle being connected to said rearward end of said bogey beam; asupport module mounted on said middle axle and extending rearwardlytherefrom for connection to a support link mounted to said frame, saidsupport module having a drive apparatus mounted thereon to provideoperative driving power to said support wheels on said middle axle; anda drive mechanism interconnecting said support wheels on said middleaxle with said rear drive wheels to transfer rotational power thereto.2. The utility vehicle of claim 1, wherein said middle axle comprises atransversely extending support beam pivotally connected to said rearwardend of said bogey beam through a central support bracket, said supportbeam having opposing lateral ends supporting respectively said supportwheels of said middle axle.
 3. The utility vehicle of claim 2, whereinsaid central support bracket is pivotally connected to said bogey beamby a pivot device that defines a longitudinally extending oscillationaxis about which said middle axle can oscillate to follow groundcontours.
 4. The utility vehicle of claim 3, wherein said pivot deviceis a ball joint.
 5. A utility vehicle comprising: a frame; a pluralityof rear drive axles mounted to the frame and having drive wheelsrotatably supported thereon; a front steering axle having a pair ofsteered wheels pivotally mounted thereon; a middle axle having a pair ofsupport wheels mounted at opposing ends thereof; and a longitudinallyextending bogey beam pivotally connected to the frame and having aforward end and a rearward end, said steering axle being connected tosaid forward end of said bogey beam and said middle axle comprising atransversely extending support beam pivotally connected to said rearwardend of said bogey beam by a pivot device that defines a longitudinallyextending oscillation axis about which said middle axle can oscillate tofollow ground contours; a support module mounted on said middle axle andextending rearwardly therefrom for connection to a support link mountedto said frame, said support module having a drive apparatus mountedthereon to provide operative driving power to said support wheels onsaid middle axle; and a drive mechanism interconnecting said supportwheels on said middle axle with said rear drive wheels to transferrotational power thereto.
 6. The utility vehicle of claim 5, whereinsaid central support bracket defines a transverse pivot axis that iseccentric with an axis corresponding to said middle axle, saidtransversely extending support beam is positioned above said rearwardend of said bogey beam.
 7. The utility vehicle of claim 6, wherein saidpivot device is a ball joint defining both said longitudinally extendingoscillation axis and said transverse pivot axis to permit bothflotational and oscillatory movements for said middle axle relative tosaid frame.